Such bases and extruded light-metal sections have become known from the 1989 issue of the "MB System" complete catalog of ITEM GmbH, Solingen. The extruded sections have a square cross section and have, on their side surfaces, grooves of an undercut design, which are intended for the introduction of fasteners. In the core area, the prior-art section has a continuous cylindrical channel, which is intended for screwing in fasteners on the front side.
Such extruded light-metal sections can be assembled into a three-dimensional framework, in which the problem is how the free spaces remaining between the posts and struts are to be covered. Wall elements, which have fittingly designed connecting elements at their edges, in order to be inserted into the grooves extending along and on the posts and struts, have been developed for this purpose. The consequence of this is the arrangement of the wall elements in the space circumscribed by the posts and the frame. However, this makes the mounting and the removal of such wall elements complicated, because these can be displaced, together with their connecting elements, only along the grooves of the posts and Struts, which is not readily possible without disassembly in a finished framework. As a consequence of this, the wall elements must be detached from their fasteners to lift them off vertically from the framework, in order to avoid this disassembly. This measure is also impractical and cumbersome especially when the base for machines and devices, in which repeated removal of the wall elements during assembly is often indispensable, is to be formed with the framework.